You need to constantly update your RasPi OS to stay secure.
The longer you put it off, the more unpatched flaws it will contain, and the more unpatched flaws your OS contains, the more likely it is that a hacker will discover one of them and use it to wreck your system or steal your data.
How to update the Raspberry Pi
Commande line
sudo apt-get update sudo apt-get dist-upgrade
Screenshot
How to update the Raspberry Pi